Created by artist Shirazeh Houshiary, the Christmas tree was unveiled today inside the gallery's Millbank building. It reimagines a similar piece she created for Tate over 20 years ago.
The work focuses on the pine tree's natural qualities – such as its texture, colour, smell and shape – while also highlighting its roots in gold leaf.
"I would like us to contemplate that the pine tree is one of the oldest species and recognise the roots are the source of its continued stability, nourishment and longevity," said the Iranian artist.
"As the roots remain hidden, it is best to seek what is hidden rather than what is apparent."
Tate formerly commissioned a contemporary artist to design its Christmas Tree every year since 1988 but paused the tradition when it commenced Caruso St John's £45 million renovation in 2013. Houshiary's tree is the first commission since.
It is suspended down the centre of the spiral staircase added by the Sterling Prize-winning firm and reaches down towards the underground public spaces.
This placement allows viewers different views from each of the three gallery levels – the tip of the tree from the lower floor, the main body from the ground, and the golden roots from the upper floor.
Tate Britain director Alex Farquharson said the unveiling marked a "pivotal moment" for the gallery.
"This tree fits the new space perfectly, allowing a different generation to experience the majesty of Houshiary's work in the striking setting of the new entrance and staircase," said Farquharson.
Elsewhere in London, Apple's Jonathan Ive and industrial designer Marc Newson have installed their own Christmas tree – an immersive "experience" in the lobby of Claridge's hotel.